Molecular Microbiology Research 2024, Vol.14, No.4, 181-187 http://microbescipublisher.com/index.php/mmr 181 Research Perspective Open Access Alternaria Leaf Spot in Cotton: Identification and Control Jiefu Lin, Yuexin Zhu Hainan Key Laboratory of Crop Molecular Breeding, Sanya, 572025, China Corresponding author: yuexin.zhu@hitar.org Molecular Microbiology Research, 2024, Vol.14, No.4 doi: 10.5376/mmr.2024.14.0020 Received: 05 Jun., 2024 Accepted: 19 Jul., 2024 Published: 06 Aug., 2024 Copyright © 2024 Lin and Zhu, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Lin J.F., and Zhu Y.X., 2024, Alternaria leaf spot in cotton: identification and control, Molecular Microbiology Research, 14(4): 181-187 (doi: 10.5376/mmr.2024.14.0020) Abstract Alternaria leaf spot (ALS) is a significant disease in cotton cultivation, affecting both yield and quality. The pathogen responsible for ALS has a complex life cycle, and its spread is influenced by environmental conditions, with various inoculum sources contributing to disease proliferation. Visual symptoms on cotton leaves and laboratory diagnostic methods are crucial for early detection and control. This study provides a detailed analysis of ALS, focusing on pathogen identification, biological characteristics, and disease management strategies. It discusses effective management approaches, including cultural practices, chemical and biological controls, and the development of resistant cotton varieties through breeding programs. Case studies from major cotton-growing regions demonstrate successful control methods and compare the effectiveness of different strategies. This study highlights the importance of integrated disease management (IDM) to ensure sustainable cotton production and offers recommendations for farmers and researchers to enhance disease control efforts. Keywords Alternaria leaf spot; Cotton cultivation; Pathogen identification; Biological characteristics; Integrated disease management (IDM) 1 Introduction Alternaria leaf spot, caused by various species of the genus Alternaria, is a prevalent foliar disease affecting cotton (Gossypium spp.) across many cotton-growing regions worldwide. The disease manifests as small, circular to irregular necrotic lesions on the leaves, often surrounded by a purple halo, which can coalesce to form larger necrotic areas, leading to significant defoliation and reduced photosynthetic capacity of the plant (Zhu et al., 2019; Nguyen and Le, 2023). In southern New Mexico, for instance, the prevalence and incidence of Alternaria leaf spot have increased due to favorable environmental conditions, with disease incidence reaching up to 100% in surveyed fields (Yu et al., 2022). Similarly, in New South Wales, Australia, outbreaks have been reported under favorable conditions, highlighting the disease's potential to cause significant damage when environmental conditions are conducive. Effective management of Alternaria leaf spot is crucial for maintaining the health and productivity of cotton crops. The disease not only affects the yield but also the quality of the cotton fiber, which can have economic repercussions for farmers. In regions like New Mexico, where the disease has become more prevalent, there is a pressing need for resistant cotton cultivars and effective disease management strategies (Zhu et al., 2018). Studies have shown that no cotton genotype is completely immune to Alternaria leaf spot under natural infection conditions, emphasizing the importance of integrated disease management approaches. Chemical treatments, such as the use of fungicides like mancozeb and propiconazole, have been shown to be effective in controlling the disease, but there is also a growing interest in eco-friendly alternatives like botanical extracts (Viriyasuthee et al., 2019; Singh et al., 2020). This study will provide a comprehensive overview of the etiology and epidemiology of cotton Alternaria leaf spot disease, evaluate the effectiveness of various disease management strategies, including chemical, plant, and genetic methods, identify current research gaps, and propose future directions for improving the management of
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